topichubs error after upgrade from 1.7 to 2.0

warning: Invalid argument supplied for foreach() in /sites/all/modules/topichubs/topichubs.module on line 165.

This is the error I get after upgrading OP from 1.7 to OP 2.0. I do not need the topichub but I cannot disable it either as op_defaults also gets disabled. Interestingly, op_defaults is somehow connected to frontpage-featured-image. So if I disable topichubs, the images go vanished.

Also there are hundreds of errors shown in the log file, all are similar to the following:

View name 'events' is already taken

The exactly same error is found for all the content types. Moreover, the overriden feature variable do not revert when tried. May be we really need a step by step guide to upgrade. :)

Thank you.